Electronic devices, and in particular personal electronic devices such as smart phones, tablets, and laptop computers, have gone through major evolutions in the past decade. The devices themselves have become smaller and smaller, while at the same time, utilizing more and more processing power, advanced communications electronics, and fewer moving parts. For example, and most particular to aspects of the present invention, the small size of modern personal electronics has demanded that mechanical cooling systems, such as fans and other air handling devices, be removed and replaced with passive cooling systems. However, the higher processing power and demands of modern electronic devices only adds to the heat generated by these devices. The temperatures generated by such devices have been reported widely in the news and have even led to user injuries and device damage. The use and development of smaller, faster, more powerful computer chips and electronic components in mobile phones, computers, laptops, tablets, etc. has caused a dramatic increase in the power, run time and heat generation in these components. The increased power and heat generation must be controlled to prevent overheating and damage to the components. This overheating also causes hotspots and hot areas on the surface of the device thereby causing discomfort or injury to the human user and therefore there is a need to manage this heat. This heat control is done by either removing the heat by various means or “throttling” back the power and speed of the components to reduce the generated heat. Reducing the speed and power of the components is not preferable since this creates inefficiencies, prolonged wait times for results, reduced download speeds, etc. Therefore materials are needed to both absorb or store this generated heat and subsequently rapidly remove or conduct heat away from the components. This is made more difficult by the shrinking of the component and total device area, all leading to a larger heat flux per unit area.
More notable is the fact that when the operating temperature of these devices increase, the performance of the device drops, either purposely by design, or naturally because of the inherent characteristics of solid state electronics. Many devices have built in safe modes that completely shut down the processors and other heat generating components if the operating temperature gets too high.
Electronic heat dissipation techniques require that the heat be move away from the operating electronic components and to the ambient environment. Without the benefit of fans and other mechanical cooling systems, the generated heat is merely transmitted by conduction to the exterior surface of the device or some other substrate. Thus, most devices become warm or hot to the touch during operation as heat exchangers are utilized to move the heat from the electronics to the device case. These prior methods rely solely on thermal conduction techniques to move the heat from one point to another.
The use of phase change materials (PCMs) in various industries to store and release heat is known. For example, the use of various forms and compositions of PCMs (micro-encapsulated or raw), their methods of manufacture and applications thereof have been widely disclosed. PCMs have been used widely in the textile and fabrics industries but have not been effectively utilized or disclosed in the electronics fields, particularly when utilized to effect heat storage and removal. The use of PCMs in the electronics industries has thus far been limited to mixing micro-encapsulated PCMs into an epoxy or otherwise mixing waxes and gels. No one has been able to figure out how to effectively take these materials, form them, lock them into place in a complicated and sensitive electronic assembly, maintain high latent heats with thermal conductivity while conforming to the confines of an enclosed electronic device or other processor confined within a sealed or other casing.
Thermal management materials (TMM), thermal interface materials (TIMs), heat management materials, heat spreaders, etc. all have key functions in an electronics package, i.e. to dissipate heat in order to allow higher processing speeds. More specifically, thermal interface materials and heat sinks bring the heat generating electronics components (i.e. chips, transistors, semiconductors, integrated circuits (ICs), discrete devices, batteries, etc.) into good thermal contact with the heat removal hardware.